JP4448957B2 - Magnetic measuring device and magnetic measuring method - Google Patents

Description

  The present invention relates to a magnetic measurement apparatus and a magnetic measurement method, and more particularly, to a magnetic measurement apparatus and a magnetic measurement method that perform offset correction of a magnetic sensor in azimuth measurement for detecting geomagnetism and calculating an azimuth. About.

  In general, in an azimuth measuring device that detects geomagnetism and calculates an azimuth angle, it is important to distinguish between geomagnetism (stationary magnetic field) and a magnetic field other than geomagnetism generated by a magnet fixed to the azimuth measuring device. . Magnetic fields other than geomagnetism are calculated as offsets (reference points) from the magnetic measurement data group using appropriate means, and the geomagnetism can be obtained by subtracting the offset from the magnetic measurement values. This offset varies greatly depending on the attachment and removal of a magnetic material (for example, a memory card) attached to the azimuth measuring device.

  FIG. 6 is a flowchart illustrating the operation of the conventional azimuth measuring device. First, magnetic data is acquired by the magnetic sensor (S1), and it is determined whether or not the magnetic data quantized by the A / D conversion unit is used by the data selection unit (S2). The magnetic data determined to be “used” is stored in the data buffer, and when the number of stored magnetic data exceeds a predetermined specified value, the oldest magnetic data is discarded from the data buffer (S5). If the number of magnetic data stored and stored is less than or equal to the predetermined specified value, the newly acquired magnetic data is added to the data buffer (S4), and the operations from S1 to S3 are repeated.

  When the oldest magnetic data is discarded from the data buffer in S5 described above, next newly acquired magnetic data is added to the data buffer (S6). The magnetic data group (a plurality of data) in the data buffer is determined by the data buffer suitability determination unit as to whether or not it is suitable for offset calculation (S7), and the magnetic data group in the data buffer determined as “suitable” The offset is calculated by the offset calculation unit (S8). If the data buffer suitability determination unit does not determine “suitable”, the process returns to S1 described above.

  The offset calculated in S8 is determined by the offset quality determination unit (S9), and the offset determined as “good” is adopted and updated as an offset correction calculation offset by the offset correction calculation unit (S10). When the offset quality determination unit does not determine “good”, the process returns to S1 described above. In this way, the quantized magnetic data is corrected using the offset adopted at that time, and the azimuth calculation unit calculates the azimuth and outputs it.

  About offset, it is disclosed by patent document 1, for example. The thing of this patent document 1 correct | amends the offset of the magnetic sensor in an azimuth measuring device, and offset information with respect to each axis | shaft output of a magnetic sensor can be calculated only by changing the direction of a mobile telephone arbitrarily. Thus, the offset calibration work is facilitated to reduce the burden on the user when performing offset calibration.

  Further, as shown in Patent Document 1 described above, the offset coordinates can be estimated by a statistical method so that the variation in distance from the obtained magnetic data to the offset is minimized. Specifically, since magnetic data is distributed on a spherical surface centered at the offset, if the center coordinates of the sphere on which the magnetic data is distributed are obtained, that is, the offset.

  In such a magnetic measurement method, the range in which magnetic data is distributed is not limited. For example, the magnetic data acquired when the user moves the azimuth measuring device in a circle may be used, or the user may walk while holding the hand. Magnetic data acquired when the hand naturally shakes may be used. For this reason, it is possible to realize offset calibration by simply changing the measured value during movement or normal operation of the magnetic measurement device without any user awareness of offset calibration. It is possible to eliminate the burden on the user when performing the operation.

  In addition, when calculating the azimuth angle by the geomagnetic sensor, in order to correct the influence of the magnetization of the vehicle body and the surrounding magnetic field using the biaxial geomagnetic sensor without using the triaxial geomagnetic sensor, A sensor that has been calibrated has already been proposed (see, for example, Patent Document 2).

  Moreover, as a conventional azimuth measuring device, the thing of patent document 3 is proposed. This patent document 3 is a vehicle geomagnetic sensor that detects the geomagnetism with a geomagnetic sensor and determines the traveling direction of the vehicle by measuring the direction and magnitude of the geomagnetism. The data trajectory related to the traveling direction is divided into 16 equiangular azimuth regions around the origin O of the XY coordinate plane. The average value is obtained from the data for each azimuth region.

  Moreover, the thing of patent document 4 detects the component measured with the magnetometer periodically, and suppresses a disorder | damage | failure so that a short-time magnetic field change may not have an effect | action to a magnetometer in that case Thus, the direction of the geomagnetism is calculated to obtain the direction of the geomagnetism and the traveling direction of the vehicle. The measurement data is divided into quadrants, and the offset is updated when the data accumulates in a specific number of quadrants.

  In addition, the device described in Patent Document 5 measures the azimuth based on the geomagnetism detected using the Hall element, and the reference value of the X-axis Hall element and the Y-axis Hall element is stored in the correction value storage unit. The correction calculation unit is configured to correct the output amplification values of the X-axis Hall element and the Y-axis Hall element by using this reference value, and to extract only a value proportional to each axis component of geomagnetism. Is.

  In addition, the device described in Patent Document 6 provides a highly accurate azimuth measuring device by correcting an attachment angle error between the direction of the input shaft of the geomagnetic sensor and the direction of the reference axis of the posture detecting device. And a mounting angle correction calculation unit that performs mounting angle error correction on the geomagnetic data and calculates the corrected geomagnetic data, and a coordinate conversion circuit that converts the geomagnetic data using the attitude data and outputs the geomagnetic data. And an azimuth calculation circuit for calculating an azimuth based on geomagnetic data.

  Further, the one described in Patent Document 7 detects a horizontal component of geomagnetism by dividing it into two component voltage output signals by magnetic detection coils orthogonal to each other, and the voltage output signal is detected by a micro that includes signal calibration calculation means. An azimuth angle measuring device that uses a geomagnetic sensor to calculate and output azimuth angle data for the magnetic north of a magnetic field that is input to a computer, calculates the correction value corresponding to each azimuth angle data from the microcomputer, and adds each azimuth angle data Correction processing means is provided.

International Publication No. 2004/3476 pamphlet (Japanese Patent Application No. 2003-35101) Japanese Patent Laid-Open No. 9-325029 JP 60-1510 A Japanese National Patent Publication No. 2-501854 JP 2003-65791 A JP 2003-42766 A JP-A-10-132568

  However, in the method described in Patent Document 1 described above, the offset calculation accuracy becomes worse as the magnetic data is concentrated in a narrow area on the spherical surface. This becomes more prominent as the noise in the magnetic data increases and the quantization number when the output of the magnetic sensor is quantized decreases.

  For example, when building a man navigation system with a magnetic sensor and GPS (Global Positioning System) installed in a mobile phone or PDA (Personal Digital Assistant), the magnetism can be made without making the user aware of it. Preferably, sensor offset calibration is performed. Therefore, the offset is calculated using the magnetic data acquired while the user is walking with his / her hand or the magnetic data acquired while changing the direction while viewing the map displayed on the mobile terminal. There is a need to. Such magnetic data is distributed only in a partial region on the spherical surface, and there is a problem that the calculated offset has a large error.

  Further, in the above-mentioned Patent Documents 3 and 4, in order to calculate the offset after a predetermined number of data is stored in all the areas obtained by dividing the measurement time, it is not always necessary at the time of use such as a portable device. When data cannot be stored in all areas divided into spaces, there is a problem that an offset cannot be calculated. In Patent Documents 3 and 4, when a plurality of data is stored in each area obtained by dividing the space, the representative value is taken or an average value is calculated and used for offset calculation. Even if there is a bias in the distribution of data, the calculated offset is treated as a good one.

  The present invention has been made in view of such a problem, and an object of the present invention is to improve the reliability of offset of a magnetic sensor when calculating a magnetic field other than geomagnetism as an offset. And providing a magnetic measurement method.

The present invention was made to achieve such an object, and the invention according to claim 1 is a magnetic measurement device that performs offset correction in azimuth measurement for detecting terrestrial magnetism and calculating azimuth. Magnetic detection means for repeatedly detecting magnetism in a two-dimensional or three-dimensional measurement space divided into a plurality of regions, storage means for storing magnetic data acquired by the magnetic detection means, and storage means stored in the storage means Based on the distribution information calculated by the distribution information calculation means, the distribution information calculation means for calculating the distribution information consisting of the number of areas where the magnetic data is distributed and the number of magnetic data in each area from the magnetic data , An offset quality determination unit that determines whether or not to use an offset calculated from the stored magnetic data group, and an offset is employed by the offset quality determination unit If it is determined, characterized by comprising an offset correction calculation unit which performs offset correction by using the adopted offset.

The invention according to claim 2 determines whether or not the invention according to claim 1 is suitable for calculating the offset of the acquired data group based on the distribution information acquired by the distribution information calculating means. A data buffer suitability determining means for performing offset calculation based on a magnetic data group determined to be suitable for calculating an offset by the data buffer suitability determining means. .

The invention according to claim 3 is the invention according to claim 2 , further comprising offset reliability information calculation means for calculating reliability information of the offset based on the distribution information, and the offset reliability information is It is characterized by output to the outside .

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the magnetic data distributed in a region having the largest number of magnetic data among the plurality of regions is the most. The old magnetic data is discarded from the storage means.

According to a fifth aspect of the present invention, in the invention of the fourth aspect , the storage means stores the oldest magnetic data among all the magnetic data stored for offset calculation at an arbitrary time interval. It is characterized by discarding.

According to a sixth aspect of the present invention, there is provided a magnetic measurement apparatus for performing offset correction in azimuth measurement for detecting geomagnetism and calculating an azimuth angle, wherein repetitive magnetism is performed in a three-dimensional measurement space divided into a plurality of regions. A magnetic detection means for detecting the magnetic data, a storage means for storing the magnetic data acquired by the magnetic detection means, and from the magnetic data stored in the storage means, the number of areas in which the magnetic data is distributed and Distribution information calculation means for calculating distribution information consisting of the number of magnetic data, and whether to use an offset calculated from a stored magnetic data group based on the distribution information calculated by the distribution information calculation means Offset quality determining means, and when the offset quality determining means determines that the offset is to be adopted, the offset compensation is performed using the adopted offset. And a offset correction calculation unit for performing the region, characterized in that it is a region partitioned by three planes perpendicular to each other.

According to a seventh aspect of the present invention, there is provided a magnetic measurement method for performing offset correction in azimuth measurement for detecting terrestrial magnetism and calculating an azimuth angle, in a two-dimensional or three-dimensional measurement space divided into a plurality of regions. A magnetic detection step for repeatedly detecting magnetism, a storage step for storing the magnetic data acquired by the magnetic detection step, and a number of regions in which the magnetic data is distributed based on the magnetic data stored by the storage step A calculation step for calculating distribution information including the number of magnetic data distributed in each region, and an offset calculated from a stored magnetic data group based on the distribution information calculated by the calculation step . A determination step for determining whether or not to adopt the offset when the determination step determines that the offset is to be adopted. There are characterized by having a offset compensation step of performing an offset correction.

Further, in the invention described in claim 8 , in the invention described in claim 7 , based on the distribution information calculated by the calculating step, it is determined whether or not the stored magnetic data group is suitable for calculating the offset. A data suitability determining step for determining , and an offset calculating step for performing offset calculation based on the magnetic data group determined to be suitable for calculating the offset in the data suitability determining step .

According to a ninth aspect of the present invention, in the invention of the sixth or seventh aspect , the magnetic data stored in the storing step is distributed in a region having the largest number of magnetic data among the plurality of regions. The method further comprises a discarding step of discarding the oldest magnetic data among the magnetic data to be performed.

According to a tenth aspect of the present invention, in the invention according to the ninth aspect , in the discarding step, the oldest magnetic data among all the magnetic data stored for offset calculation is replaced at an arbitrary time interval. The method further comprises a second discarding step for discarding.

A magnetic measurement apparatus according to the present invention includes a magnetic detection means for repeatedly detecting magnetism in a two-dimensional or three-dimensional measurement space divided into a plurality of regions, and a storage means for storing magnetic data acquired by the magnetic detection means. And distribution information calculation means for calculating distribution information comprising the number of magnetic data distribution areas and the number of magnetic data in each area from the magnetic data stored in the storage means, and the distribution information calculation means Employed when it is determined that the offset is determined to be adopted by the offset quality determining means that determines whether or not to use the offset calculated from the stored magnetic data group based on the distributed information. since a offset correction calculation unit that performs the offset correction using the offset, region magnetic data how much on the sphere It can be observed either distributed, to calculate the reliability information of the calculated offset.

  Also, it is possible to provide a method for selectively storing magnetic data and distributing the magnetic data over a wide area on the spherical surface.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram for explaining a first embodiment of the magnetic measuring apparatus of the present invention. The azimuth angle measuring apparatus according to the first embodiment includes a three-axis magnetic sensor 21 including an x-axis magnetic sensor 21a, a y-axis magnetic sensor 21b, and a z-axis magnetic sensor 21c (hereinafter also referred to as a magnetic sensor in the description of the embodiment). Have. The A / D conversion unit 25 quantizes the output of the magnetic sensor 21 amplified by the magnetic sensor amplification unit 24 via the multiplexer unit 22 driven by the magnetic sensor drive power supply unit 23.

  The data sorting / selection unit 26 determines whether to use the magnetic data quantized by the A / D conversion unit 25. The data buffer 27 for offset calculation stores the magnetic data determined to be “used” by the data selection unit 26, and when the storage capacity of the data buffer 27 is exceeded by newly added magnetic data. Is to discard the oldest magnetic data in the quadrant with the largest number of data held selected by the discard data selection unit 28.

  Based on the magnetic data stored in the data buffer 27, the data distribution information calculation unit 29 calculates the number of regions in which the magnetic data is distributed and the number of magnetic data distributed in each of the regions for each region. Is.

  The data buffer suitability determination unit 30 determines whether or not the magnetic data group in the data buffer 27 is suitable for offset calculation, and the number of regions calculated by the data distribution information calculation unit 29 and the magnetic data in each region. It is determined whether or not the number is not less than a specified value. The offset calculation unit 31 calculates an offset from the magnetic data group in the data buffer 27 determined to be “suitable” by the data buffer suitability determination unit 30.

  The offset quality determination unit 32 determines the quality of the offset calculated by the offset calculation unit 31. The offset correction calculation unit 33 adopts and updates the offset determined as “good” by the offset quality determination unit 32 as an offset for offset correction calculation, and corrects the offset using the updated offset. The azimuth calculation unit 34 calculates and outputs the azimuth based on the corrected offset. The offset reliability information calculation unit 35 outputs reliability information based on the distribution information calculated by the data distribution information calculation unit 29.

The data buffer 27 described above discards the oldest magnetic data among the magnetic data distributed in the area having the largest number of usable magnetic data among the plurality of areas, and calculates the offset. The oldest magnetic data among all the magnetic data stored for the purpose is discarded at an arbitrary time interval.
In the above description, the triaxial magnetic sensor has been described. However, a biaxial magnetic sensor can be used.

  FIG. 2 is a flowchart for explaining the operation of the azimuth angle measuring apparatus according to the first embodiment shown in FIG. First, magnetic data is acquired by the magnetic sensor 21 at an appropriate sampling interval (S11), and it is determined whether or not the acquired magnetic data is used by the data selection unit 26 (S12). The magnetic data determined to be “used” is stored (saved) in the data buffer 27. When the number of stored magnetic data exceeds the specified number (S13), the oldest data in the quadrant with the largest number of data is selected by the discard data selection unit 28 and discarded (S15). If the number of stored magnetic data is less than or equal to the predetermined specified value, the newly acquired magnetic data is added to the offset calculation data buffer 27 (S14), and the above-described operations of S11 to S13 are repeated.

  When the oldest magnetic data is discarded from the data buffer 27 in S15 described above, the newly acquired magnetic data is then added to the data buffer 27 (S16). Based on the magnetic data stored in the data buffer 27, the data distribution information calculation unit 29 calculates the number of regions in which the magnetic data is distributed and the number of magnetic data distributed in each of the regions for each region. .

  The data buffer suitability determination unit 30 determines whether or not the magnetic data group in the data buffer 27 is suitable for offset calculation, and the number of regions calculated by the data distribution information calculation unit 29 and the magnetic data in each region. It is determined whether the number is equal to or greater than a specified value (S17). If the data buffer suitability determining unit 30 determines that it is “suitable”, it is further determined whether or not there is a predetermined number or more of magnetic data in a specified number of quadrants (S18). If there is, the offset calculation unit 31 calculates an offset from the magnetic data group in the data buffer 27 (S19). If it is not determined as “suitable” in S17, the process returns to S11 described above. If there is no more magnetic data than the specified number in S18, the process returns to S11 described above.

  Next, the offset calculation unit 31 determines whether the offset is good or not (S20), and adopts and updates the offset determined as “good” as an offset correction calculation offset (S21). The offset that is not determined as “good” by the offset quality determination unit 32 returns to S11 described above. In this way, the quantized magnetic data is corrected using the offset employed at that time, and the azimuth calculation unit 34 calculates the azimuth and outputs it.

  In order to reduce the error of the calculated offset, usually some measures are taken. For example, all of the acquired magnetic data may not be stored in the data buffer for offset calculation, but may be stored only when a specific condition is satisfied. The specific condition is, for example, that the distance between the newest magnetic data in the data buffer for offset calculation and the newly acquired magnetic data is calculated. It is possible to do. By satisfying this specific condition, it is possible to prevent the same magnetic data from being stored in the data buffer when the magnetic measuring device is stationary or moving only in a narrow area.

  Further, the suitability of the data buffer in which the magnetic data is stored is checked, and if it is not suitable for calculating the offset, the offset can not be calculated. As a result, it is possible to save the trouble of calculating the unreliable offset. In most cases, the suitability of the data buffer can also be checked by determining the quality of the offset. In this case, since the offset is calculated based on the determination of the suitability of the data buffer, information obtained from the calculated offset value can be used in other places. The suitability of the data buffer can be determined by, for example, the difference between the maximum value and the minimum value of the magnetic data in the data buffer. When the difference between the maximum value and the minimum value is small, the data distribution range is narrow, and an offset including a large error may be calculated.

  Further, by examining the reliability of the calculated offset and discarding the offset that is not reliable, the chance of adopting the offset including a large error can be reduced. The reliability can be checked, for example, by the following method. That is, if the most recently calculated variation in offset is greater than or equal to the specified value, the latest calculated offset is considered unreliable.

  As described above, if the magnetic data for calculating the offset is distributed only in a part on the spherical surface, the offset calculated from the magnetic data may have a large error. To avoid this, there are the following methods.

  That is, (1) The suitability of the data buffer or the reliability of the offset is determined by whether or not the magnetic data in the data buffer is distributed in a predetermined number or more in the number of areas equal to or more than a specified value. (2) Further, in addition to (1), the magnetic data in the data buffer is classified into areas, and the oldest magnetic data in the area with the largest number of data is discarded. Particularly in the case of (2), since the magnetic data in the area having a small number of data is not discarded, the number of areas in which the magnetic data is distributed hardly decreases.

  Basically, it is preferable to divide the image into a plurality of regions that have an offset as a vertex and are separated by a predetermined solid angle. There are various ways of configuring the area. For example, there is a method that considers an area (polygonal pyramid) that includes a regular polyhedron surface with an offset as a vertex, and uses these as areas. The regular polyhedron includes a regular tetrahedron, a regular hexahedron, a regular octahedron, a regular dodecahedron, and a regular icosahedron.

  In this method, each area can be taken evenly. In particular, in the case of a regular octahedron, the region is partitioned by three planes orthogonal to each other. If the orthogonal coordinate system of the measurement system is matched with three straight lines connecting the diagonal vertices of the regular octahedron, each axis (x, It is possible to classify into regions simply by determining the sign of the measured value of y, z), and the amount of calculation can be reduced. The offset used as the vertex may be used at any time, but it is preferable to use the latest adopted (updated) offset in the past.

  3 and 4 are diagrams showing an example in which a region is configured using regular octahedrons and regular icosahedrons. Although each area is not uniform, a soccer ball centered on the offset may be considered, and the area may be configured by a polygonal pyramid including each surface of the offset and the soccer ball. Further, a region may be similarly formed from the structure of fullerene molecules such as C60 and C70. In FIG. 4, regions are formed by the number of surfaces in which a triangular pyramid including one surface having an offset (origin) as a vertex constitutes one region.

  The magnitude, dip angle and declination of geomagnetism are strongly influenced by artificial structures. There is a big difference in the magnitude of geomagnetism between urban areas with dense buildings and open spaces such as parks. Furthermore, in the urban area, the geomagnetic state changes every moment with movement. For this reason, in the method of classifying the measurement data described above into regions and discarding the oldest magnetic data in the region with the largest number of data, magnetic data having different geomagnetism sizes are mixed in the data buffer. There is a possibility that. In addition to the above-described method (2), it is preferable to add a sequence for unconditionally discarding magnetic data after a predetermined time from the data buffer.

  The azimuth measuring apparatus according to the second embodiment of the present invention causes the offset quality determination unit 32 to input the calculation data from the data distribution information calculation unit 29 in the configuration diagram of the first embodiment illustrated in FIG. The determination unit 32 is configured to determine whether the number of regions calculated by the data distribution information calculation unit 29 and the number of magnetic data in each region are equal to or greater than a specified value.

  FIG. 5 is a flowchart illustrating the operation of the azimuth measuring apparatus according to the second embodiment. First, magnetic data is acquired by the magnetic sensor 21 at an appropriate sampling interval (S21), and it is determined whether or not the acquired magnetic data is to be used by the data selection unit 26 (S22). The magnetic data determined to be “used” is stored (saved) in the data buffer 27. When the number of stored magnetic data exceeds the specified number (S23), the oldest data in the quadrant having the largest number of data is selected by the discard data selection unit 28 and discarded (S25). If the number of stored magnetic data is less than or equal to the predetermined specified value, the newly acquired magnetic data is added to the data buffer 27 for offset calculation (S24), and the operations from S21 to S23 are repeated.

  When the oldest magnetic data is discarded from the data buffer 27 in S25 described above, the newly acquired magnetic data is then added to the data buffer 27 (S26). Based on the magnetic data stored in the data buffer 27, the data distribution information calculation unit 29 calculates the number of regions in which the magnetic data is distributed and the number of magnetic data distributed in each of the regions for each region. .

  The data buffer suitability determination unit 30 determines whether the magnetic data group in the data buffer 27 is suitable for offset calculation (S27). If the data buffer suitability determination unit 30 determines “suitable”, the offset calculation unit 31 calculates an offset from the magnetic data group in the data buffer 27 (S28). If it is not determined as “suitable” in S27, the process returns to S21 described above.

  Next, the offset calculated by the offset calculating unit 31 is determined to be acceptable by the offset quality determining unit 32 (S29), and when it is determined to be “good”, the prescribed number calculated by the data distribution information calculating unit 29 (S30), and if there are more than the specified number of magnetic data, the offset determined as “good” is adopted and updated as an offset for offset correction calculation (S30). S31). If it is not determined “good” in S29, the process returns to S21 described above. In S30, if there is no more than the prescribed number of magnetic data, the process returns to S21 described above.

Next, Embodiment 3 of the present invention will be described below.
When the quality of the calculated offset is judged by a higher-level application when using the offset, an index (hereinafter referred to as offset reliability information) representing an expected “offset calculation error” is output. As the reliability information, the result of the pass / fail determination of the offset may be output, or all or a part of the information used for the determination of the pass / fail of the offset may be output as it is or after some processing. The degree of accuracy that is required depends on the type of application that uses the offset and the situation in which it is used, so the system prepares only the offset calculation routine as a lower program, and the output offset If each application can determine how to use the offset reliability information related to accuracy, the application can be designed flexibly, and each application does not have to hold the offset calculator, so memory etc. It also saves money. For example, when a magnetic sensor is mounted on a mobile phone as an electronic compass, the application may be configured to employ only an offset that falls within a desired angle error.

  As the reliability information, the rank when the offset is ranked into several levels can be output. This makes it possible to easily create a routine for calculating the offset reliability in each application.

  When outputting offset reliability information, data buffer adequacy determination and offset pass / fail determination are performed to such an extent that the output of bad precision offset that is not performed or not used by any application is suppressed (for example, mathematically). Since there may be a case where the offset cannot be calculated, in that case, the offset value is not output).

  Data distribution information can be converted into reliability information and output. In this case, the number of data distribution areas that are the distribution information itself and the number of data in each area may be output, and the result of determining whether the offset is good or not (whether there are more than a specified number of data in the specified number of areas) May be. As described above, if the number of data distribution areas and the number of data in each area are output as they are, the pass / fail judgment routine in the application using the offset becomes complicated, and if only the pass / fail judgment is output, the requirements of various applications are satisfied. Since it does not become reliability information, it is preferable in practice to divide the offset into several ranks and output this rank.

  For example, when the area is divided into eight, the rank is divided as shown in Table 1 below. Since it is difficult to express how much error each rank has in terms of azimuth, it is determined from measurement data when it is actually used.

It is a block diagram for demonstrating Example 1 of the magnetic measuring device of this invention. It is a figure which shows the flowchart for demonstrating operation | movement of the azimuth angle measuring apparatus of Example 1. FIG. It is the figure which showed the case where an area | region is 8 area | regions (area | region division by a regular octahedron). It is the figure which showed the case where it is 20 area | regions (area | region division by an icosahedron). It is a figure which shows the flowchart for demonstrating operation | movement of the azimuth angle measuring apparatus of Example 2. FIG. It is a figure which shows the flowchart for demonstrating operation | movement of the conventional azimuth measuring device.

Explanation of symbols

21 3-axis magnetic sensor 21a x-axis magnetic sensor 21b y-axis magnetic sensor 21c z-axis magnetic sensor 22 multiplexer unit 23 magnetic sensor drive power supply unit 24 magnetic sensor amplification unit 25 A / D conversion unit 26 data selection unit 27 data buffer 28 discard Data selection unit 29 Data distribution information calculation unit 30 Data buffer suitability determination unit 31 Offset calculation unit 32 Offset quality determination unit 33 Offset correction calculation unit 34 Azimuth angle calculation unit 35 Offset reliability information calculation unit

Claims (10)

In a magnetic measurement device that performs offset correction at the time of azimuth measurement for detecting geomagnetism and calculating azimuth,
Magnetic detection means for repeatedly detecting magnetism in a two-dimensional or three-dimensional measurement space divided into a plurality of regions;
Storage means for storing magnetic data acquired by the magnetic detection means;
Distribution information calculating means for calculating, from the magnetic data stored in the storage means, distribution information consisting of the number of regions in which the magnetic data is distributed and the number of magnetic data in each region ;
An offset quality determination unit that determines whether or not to adopt an offset calculated from a stored magnetic data group based on the distribution information calculated by the distribution information calculation unit;
A magnetic measurement apparatus comprising: an offset correction calculation unit that performs offset correction using an offset that is adopted when the offset is determined to be adopted by the offset quality determination unit . Based on the distribution information acquired by the distribution information calculation means, the data buffer suitability determination means for determining whether or not the offset of the acquired data group is suitable for calculation , and the data buffer suitability determination means for calculating the offset The magnetic measurement apparatus according to claim 1, further comprising an offset calculation unit that performs an offset calculation based on a magnetic data group determined to be suitable . 3. The magnetic measurement apparatus according to claim 2 , further comprising offset reliability information calculation means for calculating the reliability information of the offset based on the distribution information, and outputting the offset reliability information to the outside . Among the magnetic data distributed in regions most number of magnetic data is large among the plurality of regions, according to any one of claims 1 to 3, characterized in that discarding the oldest magnetic data from the storage means Magnetic measuring device. 5. The magnetic measurement apparatus according to claim 4 , wherein the storage unit discards the oldest magnetic data among all magnetic data stored for offset calculation at an arbitrary time interval. In a magnetic measurement device that performs offset correction at the time of azimuth measurement for detecting geomagnetism and calculating azimuth,
Magnetic detection means for repeatedly detecting magnetism in a three-dimensional measurement space divided into a plurality of regions;
Storage means for storing magnetic data acquired by the magnetic detection means;
Distribution information calculating means for calculating, from the magnetic data stored in the storage means, distribution information consisting of the number of regions in which the magnetic data is distributed and the number of magnetic data in each region;
An offset quality determination unit that determines whether or not to adopt an offset calculated from a stored magnetic data group based on the distribution information calculated by the distribution information calculation unit;
An offset correction calculation unit that performs offset correction using the employed offset when it is determined by the offset quality determination unit that the offset is employed;
And the region is a region partitioned by three planes orthogonal to each other. In a magnetic measurement method for performing offset correction in azimuth measurement for detecting geomagnetism and calculating azimuth,
A magnetic detection step for repeatedly detecting magnetism in a two-dimensional or three-dimensional measurement space divided into a plurality of regions;
A storage step of storing the magnetic data acquired by the magnetic detection step;
Based on the magnetic data stored in the storage step, a calculation step for calculating distribution information including the number of regions in which the magnetic data is distributed and the number of magnetic data distributed in each region;
A determination step for determining whether to employ an offset calculated from a stored magnetic data group based on the distribution information calculated by the calculation step;
A magnetic measurement method comprising: an offset correction step for performing offset correction using the employed offset when it is determined that the offset is employed in the determination step . Based on the distribution information calculated by the calculating step, a data suitability determining step for determining whether or not the stored magnetic data group is suitable for calculating the offset, and suitable for calculating the offset in the data suitability determining step. The magnetic measurement method according to claim 7 , further comprising: an offset calculation step for performing an offset calculation based on the magnetic data group determined to be . The method further comprises a discarding step of discarding the oldest magnetic data among the magnetic data distributed in the region having the largest number of magnetic data among the plurality of regions from the magnetic data stored in the storing step. The magnetic measurement method according to claim 7 or 8 . The discarding step, according to claim 9, further comprising the oldest magnetic data of all the magnetic data stored in the offset calculations, the second discarding step discarded at any time interval Magnetic measurement method.

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